The invention relates to the problem of providing scene-brightness-dependent control of flash duration when the flash unit being employed is of the flashbulb type.
It is known to effect scene-brightness-dependent control of flash duration when the flash unit is of the type employing an electronic flash lamp. This is conventionally effected by utilizing an automatic scene-brightness-dependent flash-duration control circuit. The control circuit includes a light sensor positioned to receive scene light, a light-measuring circuit operative for generating a signal indicative of the total of received scene light, and a threshold circuit operative for detecting when the total of received scene light has reached a predetermined value and in response to such detection terminating the flash being produced by the electronic flash lamp.
More particularly, the present invention relates to the problem of providing such flash-duration control means for the control flashbulb flash units.